Einstein to Roosevelt, August 2, 1939

In the summer of 1939, six
months after the discovery of uranium fission, American newspapers
and magazines openly discussed the prospect of atomic energy.
Most American physicists, however, doubted that atomic energy or
atomic bombs were realistic possibilities. No official U.S. atomic
energy project existed.

Hungarian-born physicist Leo Szilard was profoundly
disturbed by the lack of American action. He had conceived the idea of a nuclear chain reaction in 1933,
and kept his ideas from publication with a secret British patent. He had warned colleagues about the danger for years. Yet even
the discovery of uranium fission, followed by proof that it released neutrons, had not lessened their disbelief.

If atomic bombs were possible,
as Szilard believed they might be, Nazi Germany could gain an unbeatable lead
in developing them. It was especially troubling that Germany had
stopped the sale of uranium ore from occupied Czechoslovakia.

Unable to find official
support, and unable to convince Enrico Fermi of the need to continue
their experiments at Columbia University, Szilard turned to his old friend Albert Einstein. He had
collaborated with Einstein in Berlin in the 1920s on the invention of novel refrigerators without moving parts.
Now, he sought Einstein’s help about a very different matter.

Einstein was enjoying a
sailing vacation in Peconic on the northern tip of Long Island, New
York. On or about July 12, Szilard and fellow Hungarian physicist
Eugene Wigner made the short drive from Manhattan in Wigner’s car.
Einstein, true to his simple tastes, greeted his visitors wearing an
undershirt and rumpled, rolled-up pants. He showed them to his
cabin’s large, screened-in porch.

Szilard explained the
state of international research on uranium and the evidence that a
bomb might be possible. Given the seriousness of the situation,
Szilard’s request was quite modest. He asked if Einstein would warn
the Belgian Queen Mother, whom he knew, to prevent the large
stockpile of uranium ore in the Belgian Congo from falling into Nazi
hands. Einstein agreed to the idea, but he preferred to write to
another friend, the Belgian ambassador. Einstein dictated a letter
in German, which Wigner took down.

Einstein and Szilard re-enact their discussion for 1946 documentary

Within days, however, the
plan became much more far-reaching when Szilard discussed the matter
with economist Alexander Sachs. Sachs, who was an unofficial adviser
to President Franklin Roosevelt, urged that Einstein should write
directly to the President. If Einstein wrote such a letter, Sachs
promised to deliver it to the President personally.

If they could gain the ear
of the President, the Belgian uranium ore became a minor issue.
Szilard produced a four-page draft letter, which he
mailed to Einstein on July 19. By telephone, Einstein asked to
discuss it with Szilard in person.

In the last days of July,
Szilard returned to Einstein’s vacation cabin. Because Wigner was
out of town, Hungarian physicist Edward Teller acted as Szilard’s
chauffeur. Einstein again greeted his guests informally,
wearing old clothes and slippers. He served them tea on the shady
porch while they discussed the new approach.

Einstein was willing to
write to the President. As a life-long pacifist, he opposed the
making of weapons. He had been forced to conclude, however, that pacifism
would not succeed against the Nazis, who viewed violence as an end
in itself. He could not, he decided, let his inaction give Germany sole possession
of such destructive power. His only objection was that Szilard’s
letter was long and somewhat awkward. He preferred a shorter
message stressing the main points. Einstein dictated a short draft
in German, which Szilard took down.

Over the next few days,
Szilard translated Einstein’s dictation, going through draft after
draft. In the end, he prepared both a short and a long version. On
August 2, he mailed them to Einstein. Einstein
returned both versions signed, but he expressed a preference for the
longer version. This was the version, dated August 2, that Szilard
gave to Sachs for delivery to the President.

Einstein’s letter
did not reach the President quickly, however, nor did it have much effect.
On September 1, 1939, Hitler invaded Poland and World War II began.
Sachs finally met with the President on October 11 and presented
Einstein’s letter. The President appointed a “Uranium
Committee,” but it approved only $6,000 to buy graphite and
uranium for experiments Szilard proposed. Even that small sum was
not provided promptly.

For years, as Hitler conquered Europe,
official skepticism continued to stall American progress. A
large-scale U.S. atomic project, still limited only to research, did not begin until December 6,
1941, one day before the bombing of Pearl Harbor. It became the
“Manhattan” Project in August 1942.

Several months later, thanks to Szilard’s efforts, construction of the
first nuclear reactor was completed as soon as sufficient uranium and graphite were made
available. Its design was essentially the same as he had proposed in July 1939. The reactor,
named CP-1, operated successfully at the University of Chicago on December 2, 1942.

Photos from re-enactments filmed for 1946 March of Time documentary Atomic Power, used under
license from CriticalPast. Images of Einstein letter from FDR Presidential Library.